Apparatus for converting a wheeled vehicle to a tracked vehicle

ABSTRACT

The invention relates to track systems  14, 14′  that may be used to convert steerable, all-wheel drive construction equipment to steerable, multi-track construction vehicles  10 . A preferred embodiment of the track system  14, 14′  includes a frame  60, 182  having a reinforcing enclosure  150, 230 , a plurality of track engaging rollers  82 - 86, 202 - 206 , a sprocket  102, 214 , and an endless track  76, 198  operatively connected to the frame  60, 182 . Tension on the endless track  76, 198  is maintained with two tensioning members  170, 244  operatively connected to the forwardmost roller  82, 202 . The track system  14, 14′  preferably includes a limiting apparatus  300  that is configured to restrict the rotational movement “r” of the frame  60, 182  relative to a vehicle axle  16  to which it is attached. The limiting apparatus  300  has a first component  40 , which is associated with the vehicle axle  16 , is configured and arranged to interact with a second component  262 , which is associated with the frame of the track system  14, 14 ′. Preferably, the limiting apparatus  300  is adjustable such that the range of rotational movement “r” can be varied.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/518,826, filed Jul. 6, 2009, which is a national stagefiling of PCT/US2007/025401, filed Dec. 11, 2007, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 60/874,106,filed Dec. 11, 2006, which applications are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to an apparatus for converting a wheeledvehicle to a tracked vehicle. More specifically, the present inventionrelates to track systems that may be used to convert steerable,all-wheel drive construction equipment to steerable, multi-trackconstruction vehicles.

BACKGROUND OF THE INVENTION

Steerable, all-wheel drive construction equipment are old and well knownto the art. Originally designed to operate with only a loading scoop ora bucket, these machines have, with the provision of specificallydesigned attachments, evolved into multi-purpose machines capable ofmany diverse operations. Nowadays, a steerable, all-wheel drive machinemay be configured to operate as a trencher, street sweeper, a postholedigger, a forklift, a trencher, or a boom lift, for example. Trenchersare used to dig channels, typically for laying pipes or cable, or fordrainage. Depending on the type of digging implement, a trencher may beclassified as a chain trencher, a rockwheel trencher, or a plow. A chaintrencher excavates the ground with a specialized, closed loop chain thatdigs into and removes earth, and which is driven around a rounded metalframe or boom, similar to a chainsaw. This type of trencher can be usedto excavate in situations where it is difficult, slow, or impractical tobe with traditional backhoe type excavators. In operation, the angle ofthe boom can be adjusted to control the depth of the cut. To excavate atrench, the boom is held at a fixed angle while the machine slowlytraverses forward. A rockwheel trencher is a large diameter disc that isprovided with teeth about its circumference, and is similar to acircular saw. Rockwheel trenchers can excavate harder ground than achain trencher, and is particularly useful in situations wherethe_trench traverses solid stone. On a smaller scale, rockwheeltrenchers can also be used to make incisions into pavement for roadmaintenance and/or to gain access to utilities under roads.

The cable plow is specialized form of plow that is configured to passthrough the earth with a minimum of above-surface disruption. Thetypical cable plow is an elongated blade that has a smallcross-sectional area. These types of plows are useful in situationswhere the ground is comparatively soft. In situations where the groundis sticky or hard, the plow may be vibrated so as to ease its passage asit moves along. The bottom or lower portion of the blade plow can beattached to a cable so that the cable will be pulled along with theblade as it traverses the ground, or laid down in the trench as the plowadvances.

As will be understood, such vehicles are best utilized on solid,horizontal surfaces. The present invention provides a solution to theseneeds and other problems, and offers other advantages over the priorart.

SUMMARY OF THE INVENTION

Generally, the present invention is an apparatus and method forconverting a wheeled vehicle to a tracked vehicle. The apparatus forconverting a wheeled vehicle to a tracked vehicle includes a tracksystem that is configured and arranged to be attached to existing wheelhubs of a vehicle such as construction equipment, preferably trenchersand boom lifts. A preferred embodiment of the track system includes aframe that includes a first plate and a second plate that are parallelto each other and which are connected to each other by a plurality ofstruts. The frame has a first end having a first or forewardmost rollerat the first end and a second end having a second or rearwardmostroller. The forwardmost roller is preferably operatively connected tothe frame such that it may be temporarily displaced relative to thesecond roller of the frame when the track system is in operation. Thetrack system also includes a track engaging sprocket that is connectedto the frame, and which is configured to be driven by the wheel hub towhich it is attached. The preferred frame further includes a box-likeenclosure that is secured to the exterior surface of the first plate.The enclosure directly increases the strength and rigidity of the firstplate and indirectly increases the strength and rigidity of the secondplate by way of the struts. The enclosure also reduces torsional flexingof the frame when the frame is subjected to unbalanced loading. Inanother embodiment of the present invention, particularly preferable fora track system having a track made of rubber or the like, the frame maybe further strengthened by affixing an additional plate to one or moresurfaces of the first or second plates.

In one embodiment, the frame of the present invention includes anaperture in each of the parallel plates to accommodate a respectivetensioning mechanism. Each tensioning mechanism has two ends, with oneoperatively connected to a side or end of the shaft of one of therollers (preferably the forwardmost roller) and with the other endoperatively connected to the frame. Each tensioning mechanism includesan expandable and retractable force exerting member such as a greasecylinder, hydraulic cylinder or the like. The grease cylinders areinterconnected to each other by a conduit that equalizes the pressuretherebetween and the ends of the shaft to which they are connected. Eachtensioning mechanism can also include a restoring element, such as aspring, which can operate in concert with the force exerting memberwhile in operation. In use, each force exerting member urges an end ofthe forwardmost roller outwardly relative to the second roller of theframe to increase the tension on the endless track. This positions thefirst roller in a forward position where, by virtue of the tensioningmechanism, it is able to absorb impacts when the tracked vehicleencounters an object on the ground while in operation. For example, whenthe forwardmost roller bumps into an immovable object in the trackedvehicle's path, the first roller will tend to be pushed rearwardlytowards the second roller and each of the two the force exerting memberswill be momentarily compressed. In the absence of the immovable object,the force exerting members will both urge the first roller back to itsforward operating position. The provision of a restoring element, whichserves to assist in the operation of each force exerting member, enablesthe tensioning mechanism to operate as if it were much larger andpermits the tensioning mechanism to be formed compactly.

The track system of the present invention also preferably includes alimiting apparatus that is configured to restrict the rotationalmovement of the frame relative to the axle to which it is attached.Generally, the limiting apparatus includes two operative components.More specifically, the limiting apparatus includes a first componentthat is associated with the axle of the vehicle, and a second componentthat is associated with the frame of the track system, with the firstand second components configured and arranged to engage each other atpredetermined locations as they move relative to each other. Morepreferably, the track system includes a limiting apparatus that isadjustable such that the extents to which the frame can rotate withrespect to the axle (i.e., the range or degrees of rotational motionrelative to the vehicle to which it is attached), can be varied fromaround 0 degrees to 25 degrees plus or minus; more, if desired. Thefirst component of a preferred limiting apparatus includes a collarhaving first and second sections connected to each other with fasteningelements. The collar includes at least one stop and at least onebracket, with the stop configured and arranged to cooperate with thesecond component of the limiting apparatus, and with the bracketconfigured and arranged to attach the first component of the limitingapparatus to a vehicle axle, preferably with a plurality of fasteningelements.

The second component of the preferred limiting apparatus includes alimiting assembly that may be secured to the frame of the track system.The limiting assembly preferably comprises first and second members thatinclude either shims, posts or a combination thereof configured andarranged to define the range of rotational motion available to the framerelative to the vehicle axle. As the frame rotates, the shims or postswill eventually contact the stops of the collar such that the stopsprevent the frame from moving therepast. Thus, the limiting apparatusprevents the frame from rotating beyond predetermined clockwise andcounterclockwise angles of rotation with respect to the vehicle axle.The limiting apparatus can become adjustable with the addition/removalof shims or, alternatively, repositioning the posts on the first andsecond members.

An object of the present invention is to provide a track assembly thatcan be used to convert a wheeled vehicle into a tracked vehicle.

Another object of the present invention is to provide a frame for atrack assembly that is able to resist torsional forces.

Another object of the present invention is to provide an apparatus forlimiting the rotational movement of a track assembly relative to thevehicle to which it is attached.

Yet another object of the present invention is to provide a trackassembly with a dual force, track tensioning mechanism.

Additional advantages and features of the invention will be set forth inpart in the description which follows, and in part, will become apparentto those skilled in the art upon examination of the following or may belearned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a depiction of a known, wheeled construction vehicle;

FIG. 2 is a depiction of a converted, tracked vehicle of the presentinvention;

FIG. 3 is a partially exploded view showing a track system, a wheel hubof a vehicle, and a spacing element interposed between the track systemand the wheel hub;

FIG. 4 is a top plan view of the track system, vehicle, and spacingelement FIG. 3, with the endless track of the track system removed forclarity;

FIG. 5 is a perspective view of a preferred embodiment of the spacingelement of FIGS. 3-4;

FIG. 6 is an exploded, perspective, inboard view of an embodiment of theinvention;

FIG. 7 is a perspective, outboard view of an embodiment of a trackassembly;

FIG. 8 is a perspective, inboard view of the track assembly of FIG. 7;

FIG. 9 is an elevational plan view of the track assembly of FIG. 7;

FIG. 10 is an elevational plan view of the track assembly of FIG. 8;

FIG. 11 is an exploded view of the track assembly of FIG. 7;

FIG. 12 is an exploded, rotated, perspective view of the frame, thetensioning assemblies and support rollers of the track assembly of FIG.11;

FIG. 13 is a perspective, inverted, partially exploded outboard view ofthe frame of the track assembly of FIG. 12;

FIG. 14A is a perspective inboard view of the frame of FIG. 13;

FIG. 14B is a perspective outboard view of the frame of FIG. 13;

FIG. 15 is an outboard, elevational plan view of another track system ofthe present invention;

FIG. 16A is an exploded, perspective, inboard view of the track systemof FIG. 15;

FIG. 16B is a partial, exploded, perspective view of the partial vehiclehub housing, the limiting apparatus and the spacing element of FIG. 16A;

FIG. 16C is an exploded, perspective view of an alternate collar of thepresent invention, prior to attachment to a bell housing of a vehicle;

FIG. 16D is a perspective view of the alternate collar of FIG. 16Cattached to the bell housing of the vehicle;

FIG. 16E is an exploded, perspective view of the an alternative collarof the present invention, prior to attachment to a drive wheel housingof a vehicle;

FIG. 16F is a perspective view of the alternate collar of FIG. 16Eattached to the drive wheel housing of the vehicle;

FIG. 17 is a bottom plan view of the track system of FIGS. 3-4;

FIG. 18 is an elevated perspective view of the inboard side of the frameof the track system of FIG. 15;

FIG. 19A is an elevated perspective view of the outboard side of theframe of the track system of FIG. 15;

FIG. 19B is a perspective view of the inboard side of the frame of thetrack system of FIG. 15;

FIG. 19C is a perspective view of the outboard side of the frame of thetrack system of FIG. 15, taken from below the frame;

FIG. 19D is a bottom perspective view of the inboard side of the frameof the track system of FIG. 15;

FIG. 20 is an inboard plan view of yet another track system of thepresent invention having a limiting apparatus, the limiting apparatusshown in a neutral position;

FIG. 21 is a perspective inner view of the track system of FIG. 20illustrating the cooperative engagement between the two components ofthe limiting apparatus;

FIG. 22 is a perspective inboard view of the track system of FIG. 8including a limiting apparatus;

FIG. 23 is a perspective inboard view of the track system of FIG. 15illustrating an alternative limiting apparatus;

FIG. 24A is a partially exploded, perspective view of a first member ofthe limiting apparatus;

FIG. 24B is a partially exploded, perspective rear view of the firstmember of FIG. 24A;

FIG. 24C is a partially exploded, perspective view of the first memberof FIG. 24A including attachable shims;

FIG. 25A is an inboard, elevational plan view of a track assembly in aneutral position;

FIG. 25B is an inboard, elevational plan view of the track assembly ofFIG. 25A in which the limiter assembly prevents the track assembly fromrotating beyond a predetermined counterclockwise angle;

FIG. 25C is an inboard, elevational plan view of the track assembly ofFIG. 25A in which the limiter assembly prevents the track assembly fromrotating beyond a predetermined clockwise angle;

FIG. 26 is a cross-sectional view of the track system of FIG. 15; and

FIG. 27 is an exploded view of the track hub of the track system of FIG.15.

DETAILED DESCRIPTION

FIG. 1 illustrates a generic all-wheel drive vehicle 4 having arear-mounted trenching apparatus 5A, a front-mounted backhoe 5B and aplurality of wheels 6, connected to wheel hubs at the ends of driveaxles (not shown). The wheeled vehicle 4 of FIG. 1 and vehicles havingsimilar all-wheel drive capabilities, can be converted to a trackedvehicle using track systems and methods of the present invention. FIG. 2illustrates a vehicle 12 similar to the vehicle 4 of FIG. 1. The vehicle12, which includes a rear-mounted trenching apparatus 13 (depicted as acable plow) and was originally equipped with a plurality of drive wheelsthat have been removed and subsequently replaced by a plurality of tracksystems 14′ of the present invention. The present invention is usefulfor vehicles that are designed to be able to be used on improved roadbeds as well as unimproved, off-road surfaces, and is particularlyuseful for converting wheeled vehicles such as tractors, agriculturalequipment and specialized construction equipment such as trenchers.

Now also referring to FIGS. 3-4, the typical vehicle 4 with which thetrack system(s) 14 may be used will generally include a drive axle 16that terminates with a hub 30 (i.e., an axle hub) with a flange 32 andbolts 34 to which a wheel 6 is normally attached and secured theretowith existing fastening elements such as bolts 34 and nuts 36. The hub30 is rotated about a drive axis 31 by the axle 16. Sometimes, when thewheels 6 are steerable, the hub 30 is pivotally mounted to the axle 16by way of a housing 18 (i.e., a swivel housing, a steering housing, anaxle housing, etc.). As will be understood, the housing 18, which ispivotally mounted to the axle 16 along a generally vertical axis (i.e.,a steering axis 33), may be rotated by way of a steering arm 26 that isoperatively connected to a steering knuckle 20. As illustrated in FIG.4, the knuckle 20 of a generic steering system extends outwardly andrearwardly from the housing 18 and is connected to the steering arm 26such that the housing 18 and its attached wheel 6 or in the case of thepresent invention, its attached track system 14, can swivel about thevertical axis and steer the vehicle 12 in a normal fashion. See also,FIG. 16B.

Referring now also to FIGS. 5-6, once the respective wheel 6 of thevehicle has been removed, a track system 14 of the present invention maybe connected to the axle 16. The track system 14 may be connecteddirectly to the wheel hub 30 by the bolts and nuts 34, 36 which areattached to the drive sprocket 102 of the track system when it isattached to a rigid axle 16. However, as in the case of a steerable hub18, the track system 14 may be positioned too close to the body of thevehicle and restrict the extent to which the track may be steered. Insuch a situation, the track system 14 may include a spacing element 40that is interposed between the wheel hub of the vehicle and the tracksystem, and which positions the track system 14 away from the vehicle 12such that the normal steering range is effectively maintained.Generally, the spacing element will be able to connect the existingwheel hub of a vehicle with a drive sprocket of a track system. To thatend, the spacing element will include a first set of apertures thatcorrespond to the apertures of the wheel hub of the vehicle, and asecond set of apertures that correspond to apertures of the drivesprocket of a track system. As will be understood, the first and secondsets of apertures may differ in terms of numbers and patterns, dependingupon the particular vehicle to which a track system is to be attached. Apreferred spacing element 40 includes a generally cylindrical orconically shaped body 42 having two ends 43A, 43B, with the first end43A having an inwardly extending flange 44 and the second end 43B havingan inwardly extending flange 45. The first end flange 44 includes aplurality of apertures 48 that correspond to the bolt holes of the wheelhub 30, and are designed to receive bolts 34 and to be secured theretoby nuts 36 when the spacing element 40 is attached to a wheel hub 30.The second end flange 45 includes a plurality of apertures 50 that aredesigned to receive bolts 52 that extend through apertures in a drivesprocket 214 and to be secured thereto by nuts 54 when a track system isattached to the spacing element. In this way, the drive sprocket 102 isrotated about the drive axis 31 by the hub 30 through the spacingelement 40. The body 42 of the spacing element 40 includes outer andinner recesses or channels 46, 47, which extend from ends 43A, 43B toapertures 50, 48, in flanges 45, 44, respectively. Preferably, thechannels or recesses 46, 47 have curved walls and allow access torespective apertures. This results in the first end flange 44 having asomewhat scalloped outer periphery and the second end flange 45 having asomewhat scalloped inner periphery. As will be appreciated, the recessesor channels add strength to the body, which is important as thelongitudinal length of the body increases. In addition, it will also beappreciated that the recesses or channels and serve to reduce itsoverall weight of the spacing element. It will be understood that theshape and configuration of the spacing element may varied withoutdeparting from the spirit and scope of the invention. For example, thebody of the spacing be foreshortened so that it the shape of the spacingelement is more in the nature of a plate or disc.

Now also referring to FIGS. 7-14B, a preferred track system 14 of thepresent invention generally includes a frame 60 having first and secondends 61A, 61B. More specifically, the frame 60 includes a first plate 62and a second plate 64 that are generally parallel to each other and areconnected to each other by a plurality of struts 66. Each plate 62, 64includes an inner surface 68, 69 and an outer surface 70, 71,respectively. The first and second plates 62, 64 also include anaperture 108, 110 that is sized and configured to receive a tensioningmechanism 170. Generally, the frame 60 includes an endless track drivesprocket 102, a first (or forwardmost) roller 82, a second (orrearwardmost) roller 84, and a plurality of intermediate rollers 86. Thesprocket 102, which comprises first and hemispherical second sections104, 106, with each section having outwardly extending teeth and aninwardly extending flange with apertures, is operatively connected withfastening elements to the flange of a main hub 134 (i.e., a track hub),which is attached, by conventional fastening elements, to a top wall 152of an enclosure 150 that is attached to the outer surface of the secondplate 64. Each of the first and second rollers 82, 84 are operativelyconnected by way of transverse shafts 88 to pair of shoes 90, 92, thatare received in C-shaped rails 112. Each shoe 90, 92 is generallyrectangular in shape and includes a transverse shaft bearing element 94,a first or top wall 98, a second or bottom wall 99 and an end wall 96.In addition, each shoe includes a pair of flanges 95 that extend awayfrom each other in opposite directions along the top and bottom walls.Each rail 112 includes a top wall 114, a side wall 116 and a bottom wall118, which form a C-shaped channel 120 that is configured and arrangedto slidingly receive a respective shoe. Note that the flanges 95 of eachshoe will lie adjacent the edges of the top and bottom walls of the railwhen the shoe is positioned therein. Preferably, the rails are locatedadjacent the first and second ends 61A, 61B of the frame 60 so that whenthe first and second rollers 82, 84 are connected to the frame, they areable to partially extend therebeyond and so that they are also able topartially extend below the lower extent of the frame 60.

The track system 14 preferably further includes a plurality of smallerintermediate rollers 86 (or bogey wheels) that are located in betweenthe first and second rollers 82, 84 and which are rotatably mounted toshafts 89 that are attached to flanges 132 that extend inwardly towardseach other from the inner surfaces 68, 69 of plates 62, 64, and whichare proximate the lower edges of apertures 108, 110, respectively. Theintermediate rollers 86 are configured to rotatably ride on edgesurfaces of parallel guide bars 80 that extend from an inner surface 78of the endless track 76. Preferably, the intermediate rollers 86 have athinned center portion that is arranged and configured such that theintermediate rollers 86 provide clearance for the sprocket 102 as itrotates. The inner plate 62 of the frame 60 also has an upwardlyextending, u-shaped recess 111 sized to provide clearance for thespacing element 40 so that it may freely rotate during normal operation.The track system 14 of the preferred embodiment includes a segmentedendless track 76 that may be drivingly engaged by the sprocket 102.However, as will be appreciated, the track systems of the presentinvention may be used with non-segmented endless tracks known in theart.

Tension for the endless track is maintained by dual tensioningmechanisms that are operatively connected between first roller and theframe of the track assembly. Generally, each respective tensioningmechanism includes a cylindrically shaped force exerting member havingfirst and second ends, and each tensioning mechanism is operativelyconnected to the a first roller so that is able to urge the roller in aforward direction, relative to the frame. Having dual tensioningmechanisms that are operatively connected to the first roller isnecessary in order to avoid interference with the sprocket rotation andto maintain the overall compact nature of the track assembly. Inaddition, the dual tensioning mechanisms are interconnected with eachother so that they are able to provide equal amounts of force to theends of the support shaft on which the first roller is rotatablymounted. As will be appreciated, the combined forces of the first andsecond tensioning mechanisms will have the effect of a single, muchlarger tensioning mechanism. Each of the tensioning mechanisms has aforce exerting member such as a grease cylinder (for example, a greasecylinder from Aurelius Mfg. Co., Inc., Braham, Minn.), hydrauliccylinder or the like to resist movement of the first roller in thedirection towards the second roller in response to impacts withgenerally immovable objects such as curbs. In preferred embodiments, thetensioning members of the track system are fluidly connected to eachother by a conduit, which serves to equalize the force applied to eachend of the support shaft and the respective roller associated therewith.The tensioning mechanisms of the present invention are discussed in moredetail below.

The frame 60 of the present invention further preferably includes areinforcing enclosure 150 affixed to the outer surface 70. The preferredenclosure 150 of this embodiment is box-like and includes a top wall152, bottom wall 154, first wall 156, second wall 158 and a panel 160,which are connected to each other and the outer plate so as to form aunitary structure. The enclosure 150 of the present invention directlysupports and strengthens the second plate 64, and indirectly strengthensthe first plate 62, by virtue of interconnecting struts 66. This enablesthe frame 60 to better resist flexing due to torsional forces. As willbe understood, the outer tensioning mechanism 170 of the shown tracksystem 14 is not easily accessible through the enclosure 150. However,the tensioning mechanisms 170 may be accessed from the inner side of thetrack system 14 by removing the spacing element 40, if present, and thenremoving the sprocket 102. Preferably, the sprocket 102 of the presentinvention is a split sprocket and includes first and second pieces orsections 104, 106. By carefully positioning of the sprocket 102, onlyone of the pieces 104, 106 need be removed in order to inspect, maintainor replace the tensioning mechanism 170.

The frame 60 of the present invention also draws additionalreinforcement from a plurality of parallel struts 66 that are spacedapart from each other and which extend between the first plate 62 andthe second plate 64. Preferably, the struts 66 are cylindrical and havehollow interiors 124 such that the weight of the frame 60 is reduced.One of the struts 66 may serve to house the conduit 180 that fluidlyconnects the first tensioning mechanism to the second tensioningmechanism.

For track systems 14 having endless steel tracks 76, the first roller 82is operatively connected to the frame 60 with a pair of shoes 90, 92that are configured to slide longitudinally (towards the second roller)within corresponding rails 112 connected to the inner surfaces 68 of thefirst and second plates 62, 64. The shoes 90, 92 include a first wall98, a second wall 99, and bearings 94 that are operatively connected tothe ends of a transverse shaft 88 about which the first roller 82 isrotatably mounted. The rails 112 of the present invention preferablyinclude a top wall 114, side wall 116 and bottom wall 118 that define aC-shaped channel 120. The shoes 90 of the first roller 82 can slidewithin their respective channels 120 to absorb shocks that come fromencountering immovable objects, as discussed above. The shoes 92 of thesecond roller 84 are generally immovably retained within theirrespective channels 120. In order to position the second roller 84 adesired distance from the frame 60, a spacer 100 may be positionedbetween an end wall 96 of each shoe 92 and a bracket 126, two of whichare attached to respective plates 62, 64 of the frame 60. Each bracketincludes an opening 128 through which a portion of the tensioningmechanism, including an interconnecting conduit 180, may extend. Notethat each bracket 126 is also operatively connected to one of thetensioning mechanisms 170 that absorb impacts received by the firstroller 82.

Generally, each tensioning mechanism 170 used with track systems 14having endless, segmented, steel tracks, includes a cylindrically shapedforce exerting member 172 having first and second ends, a forcerestoring element 174, and a block 176, and each tensioning mechanism isoperatively connected to the a first roller so that is able to urge theroller in a forward direction. Preferably, each block 176 is attached toa respective end 96 of a shoe 90 by fastening elements 178 so that thefirst roller 82 is able to be linearly displaced along the C-shapedrails. The restoring element 174 bears special mention. During forwardmovement of the vehicle 12, should the track assembly 14 contact anobstruction such as a curb (not shown) the first or forwardmost roller82 is forced rearwardly against the resiliency of not only thetensioning mechanisms 170, but also the restoring element 174. After theobject has been traversed, expansion of the compressed restoring element174 assists the tensioning mechanisms 170 in restoring the first orforwardmost roller 82 to its original operating position. The bracket126, against which the tensioning mechanism 170 is in contact, has anopening 128 that is circumscribed by a circular guide 130, which form acup-like structure that receives one end of the tensioning mechanism170, the resilient restoring element 174, and a portion of theinterconnecting conduit 180. The tensioning mechanism 170 of theembodiment including an endless track 76 made of steel has a preferredlength in the range of about 12.25 to about 16.25 inches (30.0-40.0 cm),more preferably about 14.25 inches (36.0 cm).

For track systems 14′ having endless rubber 198 or elastomeric tracks,the preferred frame 182 is best illustrated in FIGS. 16A, 17, 18, and19A-D. It will be noted that with this embodiment, the first and secondrollers 202, 204 (FIG. 17) are not interconnected to the frame 182 withshoes. Instead, the preferred frame 182 for use with endless rubbertracks 198 includes a pair of open ended longitudinal slots 221 on eachof the first and second ends 194, 196 of the frame 182. The tensioningmechanisms 244 include two ends, with one end of each tensioningmechanism 244 operatively connected to opposite ends of the shaftbearing 212 to which the first roller 202 is rotatably mounted, and theother ends of the tensioning mechanisms 244 operatively connected to theframe 182 by way of brackets 248 (FIGS. 16A and 19A-D) and fasteningelements 250 (FIGS. 20, 21). In operation, the tensioning mechanisms 244allow the ends of the shaft 210 of the first roller 202 to shiftposition within the slots 221 as the front of the track assembly 14′encounters and reacts to generally immovable objects. In preferredembodiments, as also described above, the tensioning mechanisms 244 arefluidly connected with a conduit 252. Additionally, as with thepreviously described embodiment, once the object has been traversed,force exerting members 246 restore the first roller 202 to its originaloperating position. As will be appreciated, the tensioning mechanisms244 for track systems 14′ having endless elastomeric tracks 198 do notnecessarily require the use of a restoring element; it is optional. And,similar to the previously described embodiment, the second roller 204 isgenerally immovable, with the ends of its support shaft 210 beingremovably retained in the longitudinal slots 221 of the second end ofthe frame 196.

Referring now in particular to FIG. 17, it is noted that the first andsecond rollers 202, 204 of this embodiment include a centrally locatedgroove or channel 208 that is sufficiently large enough to provideclearance for portions of the sprocket 214 so that it may freely rotatewithout interfering with the rollers 202, 204. Intermediate or bogeywheel rollers 206 are split apart, with two rollers attached to eitherside of the frame 182. It will be appreciated that this arrangementallows the track assembly 14′ to be configured into a compact form thatis lighter and more easily manipulated than conventional trackassemblies. While such rollers 202, 204 may be unitary in construction,it is envisioned that the each roller may comprise two separate rollersthat are configured to form a groove or channel 208 therebetween.

The frame 182 of the present invention further preferably includes areinforcing enclosure 230 affixed to the outer plate 186. The preferredenclosure 182 of this embodiment is box-like and includes a top wall232, bottom wall 234, first wall 236, second wall 238 and a panel 240,which are connected to each other and the outer plate 186 so as to forma unitary structure. The enclosure 230 of the present invention directlysupports and strengthens the outer plate 186, and indirectly strengthensthe inner plate 184, by virtue of interconnecting struts 188. Thisenables the frame 182 to better resist flexing due to torsional forces.As will be understood, the outer tensioning mechanism 244 of the showntrack system 14′ is not easily accessible through the enclosure 230.However, the tensioning mechanisms 244 may be accessed from the innerplate 184 of the track system 14′ by removing the spacing element 40, ifpresent, and then removing the sprocket 214. Preferably, the sprocket214 of the present invention is a split sprocket and includes first andhemispherical second sections 216, 217, with each section havingoutwardly extending teeth and an inwardly extending flange withapertures for attachment to the flange of a main hub 224 (i.e., a trackhub). By carefully positioning of the sprocket 214, only one of thepieces 216, 217 need be removed in order to inspect, maintain or replacethe tensioning mechanism 244. In addition, the inner plate 219 of theframe 182 also has a u-shaped recess 218 sized to provide clearance forthe spacing element 40 so that it may freely rotate during normaloperation.

For embodiments of the present invention including rubber or rubber-liketracks 198, in addition to the enclosure 230 or instead of theenclosure, the frame 182 may be reinforced by affixing an additionalplate 219 to one or more surfaces 190, 192 of the first or second plates184, 186.

A preferred track system 14′ of the present invention for vehicles 12having steerable axles 16 may include a limiting apparatus 260 torestrict the range of rotational motion of the frame 182 with respect tothe axle 16. A preferred limiting apparatus 260 of the present inventionis best illustrated in FIGS. 16B and 24A-C. Generally, the limitingapparatus 260 comprises a collar 262 that is associated with the vehicle12 to which the track assembly 14′ is being attached, and a limitingassembly 300 that is associated with the track assembly 14′ itself. Morespecifically, the collar 262 includes first and second sections 264, 266that are configured to be positioned about the exterior surface of anaxle housing, and which are removably connected to each other withfastening elements 270 inserted through apertures 268 in each of therespective sections. Preferably, each section 262, 264 includes anoutwardly extending flange or bracket 282, 284, with each bracketincluding a plurality of peripheral apertures 286 and a center aperture288. In use, the respective brackets 282, 284 of the collar 262 arepositioned over upper and lower surfaces of the swivel housing 18 at theend of the axle 16 such that the center and attachment apertures 288,286 are aligned with corresponding apertures 22, 24 in the housing 18.Then, the collar 262 is secured to the housing 18 with fasteningelements 290 such as bolts. During operation of the tracked vehicle 12,the collar 262 will remain attached to the housing 18 and will be ableto rotate about a vertical axis as the tracked vehicle 12 is steerednormally. However, the collar 262 will not rotate with respect to therotational axis 31 of the wheel axle. The frame 182 of the trackassembly 14, which is operatively connected to the wheel hub 30, will beable to rotate about the wheel hub axis 31 of the track assembly 14 asthe grade of the ground “g” changes and as the tracked vehicle 12encounters obstacles (not shown) on the ground “g”. In preferredembodiments, the collar 262 includes at least one stop, preferably afirst stop 292 a and a second stop 292 b. As depicted, the stops 292 a,292 b extend outwardly from the collar 262 in a radial direction,however it is understood that they may extend in other directionswithout departing from the spirit and scope of the invention. Each stop292 a, 292 b preferably includes two contact surfaces 294 a-b, 294 c-d,wherein the contact surfaces are configured to simultaneously engagecomponents of the limiting assembly 300, discussed below. The stops 292a, 292 b are positioned on opposite sides of a vertical reference planeRP that passes through the drive axis 31.

In situations where an axle housing 18″ adjacent a wheel hub 30″ doesnot include upper and lower surfaces with corresponding attachmentapertures, the brackets of collar may be modified so that they are ableto engage raised portions of the housing to which it is attached. In apreferred embodiment, FIGS. 16E-F, a collar 262″ may be provided with afirst bracket 282″ that includes one or more downwardly extendingflanges 282 a″ that form a channel(s) 296″ between a surface of thefirst section 264″ and the flange 282 a″. Bolts 290″ may be provided forthe flange(s) 282 a″ so that a portion of the axle housing 18″ will beable to be frictionally retained within the channel 296″. The secondbracket of the second section 266″ may be replaced with an elongated,outwardly extending bolt 298″ that is connected to a clamp block 272″having an inwardly extending channel 274″. The inwardly extendingchannel 274″ of the clamp block 272″ is configured and arranged so thatit may engage a second raised section of a housing 18′ to which it isattached. Preferably, when the bolt 298″ is tightened, the clamp block272″ is drawn up against the second raised portion of the housing 18″and the collar 262″ is secured thereto. In operation, rotation of thecollar 272″ is primarily resisted by the housing 18″, about which thecollar 262″ is nestably positioned, and to a lesser extent, theattachment bracket 282″ and clamp block 272″. Alternatively, as depictedin FIGS. 16C-D, a collar 262′ may be provided with a bracket 282′ andclamp 272′ that are used to connect the collar 262′ to a portion of asteering knuckle 20′ and flange 19′ of a bell housing 18′ that supportswheel hub 30′. More specifically, the bracket 282′ includes a flange283′ that forms a channel with a surface of the collar 262′ when thebracket 282′ is drawn up against the collar 262′. Clamp 272′ includes aninwardly facing channel that is configured to engage a portion of atransverse wall 21′ of the steering knuckle 20′. As with the previousembodiment, the rotation of the collar 262′ is primarily resisted by thehousing 18′ itself, about which it is nestably positioned. It will beappreciated that, in accordance with the present invention, the collarsof the present invention can be customized for various bell housings.

Generally, the limiting assembly 300 has a first member 302 and a secondmember 304, with each member 302, 304 having at least one flange 306with which to attach the respective members 302, 304 to the second plate186 of the frame 182 with bolts 328. The components of the limitingassembly 300 that contact the stops 292 a, 292 b of the collar 262comprise at least two posts 308, 310, 312, 314, respectively, that areconfigured to abuttingly engage one or more stops of a collar when theframe 182 has reached a maximum predetermined rotational angle.Preferably, each member 302, 304 includes two spaced apart posts 308,310, 312, 314 with the posts arranged radially about the rotational axisof the wheel hub 30 so that when the track assembly 14′ rotates ineither direction, the stops of the collar 292 a-b engage two of the(diametrically opposed) posts 308, 310, 312, 314 simultaneously and actin concert to prevent over-rotation of the track assembly 14′. Inpreferred embodiments, the first and second members 302, 304 may includeone or more channels 324 to reduce the overall weight of the respectivemembers.

In a preferred embodiment, the limiting apparatus 260 is adjustable suchthat the range of rotational motion that the frame 14′ can move withrespect to the axle 16 may be varied. In this embodiment, either theposts 308, 310, 312, 314 may be removably secured such that they may berepositioned on a respective member 302, 304 or the limiting assembly300 may be provided with removable shims 318 positioned proximate eitherside of the posts 308, 310, 312, 314 of each member 302, 304. Inpreferred embodiments, the stops 292 a, 292 b reside between the shims318, or the posts 308, 310, 312, 314 in embodiments not including shims.Shims 318 of the preferred embodiment are generally wedge shaped, havingcontact surfaces 320, and which may be secured to the first and secondmembers 302, 304 with at least one removable fastening element 321, suchas a bolt, inserted through at least one aperture 322 in each shim 318that corresponds to an aperture 326 in the respective member 302, 304.

As will be appreciated, the removal or addition of shims 318 allows therange of rotational motion in which the frame 14′ can move relative tothe axle 16 to be increased or decreased. It is preferable that theshims 318 or posts 308, 310, 312, 314 be contoured to correspond to theshape of the contact surfaces 316 of the posts and stops such that whenrespective shim or posts impact the stops of the collar 262, force isdissipated throughout larger surface areas. Even more preferably, theshims 318 are contoured such that they not only correspond to the collarstops 292 a, 292 b but also to the other shims such that the shims 318may be connected to the members 302, 304 in a juxtaposed relation asshown in FIGS. 23 and 24A-C. Moreover, the preferred shims 318 all havesubstantially the same configuration so that they may be interchangeablypositioned on either of the two members 302, 304. In preferredembodiments, the shims 318 have a radial range from about 1 to about 6degrees. As an alternative to having a limiting assembly withconfigurable or positionable posts, it is envisioned that the stops of acollar may be modified to achieve the same result. That is, the contactsurfaces of the stops may be effectively widened or narrowed, asdesired.

For example, FIGS. 25A-25C illustrate how the limiting apparatus 260restricts movement of the track assembly 14′ relative to the axle 16 ofa vehicle 12 that is traversing uneven or undulating ground “g”. FIG.25A shows an inboard view of a track assembly 14′ and a limitingapparatus 260, with the collar 262 attached to exterior of an axlehousing, and with the limiting assembly 300 attached to frame 182. Inthis depiction, the track assembly 14′ is in a generally horizontalposition, wherein the stops of the collar are positioned between shims318. Note that rotational movement available to the track assembly 14′is approximately the same in the clockwise and counterclockwisedirections. As best depicted in FIG. 25B, the range of rotational motion“r” is defined by the distances between each post 308, 310, 312, 314 andthe contact surfaces 294 a-d of the stops 292 a, 292 b (or defined bythe distances between shims and the contact surfaces of the stops, asthe case may be), may rotate without contacting a stops 292 a, 292 b.Thus, if a user wanted to increase the range of rotation for a trackassembly represented by “r1”, one would remove an appropriate number ofshims, and the increased range would be expanded to the representation“r2” in FIG. 25B. In FIG. 25B the track assembly 14′ is depicted aspitching forward and in FIG. 25C the track assembly 14′ is depicted arearing backward. When the frame 14′ has reached the predeterminedmaximum degrees of rotational movement “r2” with respect to the axle 16,the posts or shims 308, 310, 312, 314, 318 are blocked by thediametrically opposed stops 292 a, 292 b such that the frame 14′ isprevented from moving any further in that direction.

Referring to FIGS. 26 and 27, the track hub 224 includes a hub shaft 235that rotates with a hub flange 237 (i.e., a sprocket flange). The hubshaft 235 is supported by a bearing 239 mounted within a hub housing 241fastened to the top wall 232 of the reinforcing enclosure 230. Thespacer 40 and the sprocket 214 are attached to the hub flange 237 byfasteners 52 that extend through openings 50 of the spacer 40. Thespacer 40 is attached to the drive hub 30 by fasteners 34 (see FIG. 16B)received in openings 48 defined by the spacer 40. The track hub 224allows the drive sprocket 214 to be rotated relative to the frame 182about the drive axis 31. The sprocket 214 is rotated about the driveaxis 31 by torque from the axle hub 30 that is transferred from the axlehub 30 to the drive sprocket 214 through the spacer 40. The track hub224 also allows the frame 182 to pivot about the drive axis 31 as shownat FIGS. 25B and 25C.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the present invention have been setforth in the foregoing description, together with details of thestructure and function of various embodiments of the invention, thisdisclosure is illustrative only, and changes may be made in detail,especially in matters of structure and arrangement of parts within theprinciples of the present invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed.

What is claimed is:
 1. A track system comprising: a frame having a firstend and a second end, the frame having inboard and outboard frameassemblies that extend between the first and second ends of the frame; adrive sprocket mounted between the inboard and outboard frame assembliessuch that the inboard frame assembly is inboard of the drive sprocketand the outboard frame assembly is outboard of the drive sprocket, thedrive sprocket being rotatable relative to the frame about an axis ofrotation; a first end roller mounted at the first end of the frame; asecond end roller mounted at the second end of the frame; a track routedin a generally triangular path about the drive sprocket and the firstand second end rollers, the track being driven by the drive sprocketabout the generally triangular path when the drive sprocket is rotatedabout the axis of rotation; and inboard and outboard cylinders formoving the first end roller relative to the frame to tighten the track,the inboard and outboard cylinders being in fluid communication with oneanother, the inboard cylinder being inboard of the drive sprocket andthe outboard cylinder being outboard of the drive sprocket; wherein thegenerally triangular path of the track has an apex, and wherein thedrive sprocket engages the track adjacent the apex to drive the trackabout the generally triangular path; and wherein the track defines abottom side of the generally triangular path that extends between thefirst and second end rollers, wherein the track system includes first,second, third and fourth intermediate rollers for supporting the trackalong the bottom side of the generally triangular path, wherein thefirst, second, third and fourth intermediate rollers are positionedbetween the inboard and outboard frame assemblies, wherein the first,second, third and fourth intermediate rollers are respectively mountedon first, second, third and fourth cantilevered shafts, wherein thefirst and third cantilevered shafts are supported by the inboard frameassembly and the first and third intermediate rollers are respectivelymounted on the first and third cantilevered shafts adjacent the inboardframe assembly, wherein the second and fourth cantilevered shafts aresupported by the outboard frame assembly and the second and fourthintermediate rollers are respectively mounted on the second and fourthcantilevered shafts adjacent the outboard frame assembly, and whereinthe drive sprocket passes between the first and second intermediaterollers and between the third and fourth intermediate rollers as thedrive sprocket is rotated about the axis of rotation.
 2. The tracksystem of claim 1, wherein the first and second cantilevered shafts areco-axially aligned and the third and fourth cantilevered shafts areco-axially aligned.
 3. The track system of claim 2, wherein the firstand second end rollers are positioned between the inboard and outboardframe assemblies and are mounted on end roller shafts each supported bythe inboard and outboard frame assemblies.
 4. The track system of claim3, wherein the first and second end rollers each include first andsecond flanges, and wherein the drive sprocket passes between the firstand second flanges of the first and second end rollers as the drivesprocket is rotated about the axis of rotation.
 5. The track system ofclaim 4, wherein the inboard and outboard frame assemblies areinterconnected at a first interconnection location positioned above thefirst end roller, wherein the inboard and outboard frame assemblies areinterconnected at a second interconnection location positioned above thesecond end roller, wherein the inboard and outboard frame assemblies areinterconnected at a third interconnection location positioned betweenthe first end roller and the first and second intermediate rollers, andwherein the inboard and outboard frame assemblies are interconnected ata fourth interconnection location positioned between the second endroller and the third and fourth intermediate rollers.
 6. The tracksystem of claim 5, wherein the first and second interconnectionlocations include struts that extend between the inboard and outboardframe assemblies.
 7. The track system of claim 6, wherein a conduit forfluidly connecting the first and second cylinders passes through thestrut of the first interconnection location.